Prenatal diagnosis of ostium secundum atrial septal defect by M-mode fetal echocardiography.

Advances in fetal echocardiography enable the prenatal diagnosis of a vast majority of congenital heart defects. On the other hand, ostium secundum atrial septal defect is difficult to diagnose in the fetus. Although a defect of minor clinical significance, this may be the only intrauterine finding of a chromosomal anomaly. We documented an abnormal oscillatory pattern of the foramen ovale flap motion by M-mode fetal echocardiography in 2 fetuses with ostium secundum atrial septal defect. This may be a more consistent finding for the prenatal diagnosis of ostium secundum atrial septal defect than the previously reported bidirectional flow across the foramen ovale on color Doppler sonography.